(a) Field of the Invention
The present invention relates to a method of requesting resources, a method of allocating resources, and an apparatus therefor by using bandwidth request ranging in a mobile communication system. More particularly, the present invention relates to a method in which a subscriber station requests resources required for transmission of uplink traffic and in which a base station allocates the requested resources, and an apparatus therefor.
(b) Description of the Related Art
FIG. 1 is a flowchart illustrating a procedure of a broadcasting system for broadcasting information in a portable Internet system.
In the portable Internet system, ranging is classified as initial ranging, periodic ranging, bandwidth request (BR) ranging, and hand-off ranging.
The BR ranging is used to request resources that are necessary for a subscriber station to transmit traffic through an uplink. As shown in FIG. 1, a base station (AP: Access Pointer) broadcasts code division multiple access (CDMA) code information as system information used for BR ranging, which is included in an uplink channel descriptor (UCD). The base station broadcasts information on the uplink resources to all subscriber stations, and the subscriber stations use the uplink resources to transmit a BR code through a UL-MAP.
FIG. 2 is a view illustrating a BR ranging procedure in a portable Internet system.
Referring to FIG. 2, the BR ranging procedure is performed in the current portable Internet system, as follows.
When uplink traffic occurs, a subscriber station performs BR ranging in order to transmit the uplink traffic as shown in FIG. 2. More specifically, the subscriber station selects an arbitrary BR code included in the UCD and transmits the selected BR code to the base station in a competition scheme by using resources allocated to the UL-MAP (S210).
Next, when the BR code is successfully received without conflict, the base station broadcasts CDMA_Allocation_IE of the UL-MAP including a frame number of the BR code received from the subscriber station, subchannel information, a received BR code number, and bandwidth allocation information that the subscriber station needs in order to transmit a BR header (S220).
Next, the subscriber station compares the frame number, the subchannel information, and the bandwidth request code number of the CDMA_Allocation_IE included with information that the subscriber station transmits in order to perform the BR ranging. If the information is the same, the subscriber station transmits the BR header by using the uplink resources allocated to the base station (S230). Here, the BR header includes resource information that the subscriber station needs in order to transmit the uplink traffic.
Next, when the BR header is received, the base station allocates the uplink resources with respect to the resources requested by the subscriber station and broadcasts associated information through the UL-MAP (S240). When the resources requested through the UL-MAP are allocated, the subscriber station transmits the uplink traffic.
As described above, in order to transmit the uplink traffic in the portable Internet system, the subscriber station transmits the BR code and is allocated the uplink resources from the base station. In this case, a total of 9 frames are delayed, so there is a problem in that a transmission delay of the uplink traffic increases. Particularly, the transmission delay of the uplink traffic results in an increase in the time taken for transmission of an uplink ACK on a packet that is received through a downlink in a transmission control protocol (TCP)-based Internet service, so there is a problem in that downlink traffic transmission speed is decreased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.